TPW Roads

Chalk Hill Road Bridge Replacement


The existing bridge that carries Chalk Hill Road over Maacama Creek has been identified as seismically-deficient and poses a risk to roadway users including bicyclists, pedestrians, and emergency services. The existing bridge has deteriorated significantly and is vulnerable to earthquakes as well as foundation scour and erosion.

The County of Sonoma, in cooperation with the State of California, seeks to replace the bridge with a new two-lane bridge. The replacement project is funded by the Federal Highway Administration under the Highway Bridge Program, which is administered by Caltrans.  

Project Goals, Status, and Timeline

Project Goals:

  • Replace existing bridge with a bridge that meets modern design and construction standards
  • Design a bridge that reflects local character and environment
  • Improve safety and access for drivers, pedestrians, cyclists, and emergency services

Project Status:

The Project Team has completed their technical field investigations and has held three community outreach meetings. Based on the feedback from the community outreach meetings the Project Team has determined that the existing bridge will be removed and has selected the bridge alignment and roadway width as seen here:

Chalk Hill Bridge

Chalk Hill Bridge Width

Estimated Timeline:

In Spring/Summer 2019, the Project Team conducted technical studies and community workshops designed to inform the public about the project and the development of design alternatives. Environmental studies will take place from 2019 – 2021, with a final bridge design expected in 2021. Bridge construction is expected to take place in 2022-2023.

Based on the feedback received from the Third Community Meeting, the Project Team is conducting further study and preliminary design work to guide the next step of the bridge replacement process. A fourth community meeting is expected to take place in Winter 2019/2020 to provide a project update and present the selected bridge type.

Please feel free to email us at with any questions.

    Community Outreach & Next Steps

    The Project Team has held three community outreach meetings at the Alexander Valley Hall to discuss the replacement of the Chalk Hill Road Bridge.

    February 19, 2019: First Community Meeting

    The purpose of the meeting was to:

    • Describe the need for the project
    • Describe the key project constraints
    • Seek community input regarding future use of the existing bridge
    • Seek community input regarding design of the replacement bridge

    Based on community comments at this meeting, there appears to be a consensus to:

    • Remove the existing bridge
    • Locate the replacement bridge near the existing alignment
    • Keep design speeds low
    • Minimize roadway width

    June 4, 2019: Second Community Meeting 

    The purpose of the meeting was to:

    • Review Community Meeting #1
    • Present conclusions drawn from community comments
    • Provide project update
    • Seek community input on design considerations

    Based on community comments at this meeting, the consensus is:

    • Remove the existing bridge
    • Build new bridge on parallel alignment
    • Select the roadway configuration that meets use and safety requirements while minimizing impacts to the natural environment
    • Bridge type concepts should reflect or enhance the rural bucolic setting

    October 1, 2019: Third Community Meeting  

    The purpose of the meeting was to:

    • Review Community Meetings #1 and #2
    • Present conclusions drawn from community comments
    • Provide project update
    • Present bridge type concepts and scour countermeasures for community feedback

    July 21, 2021 from 6pm-8pm: Fourth Community Meeting

    Please register at Topics will include:

    • Project overview
    • Project update
    • Selected bridge type
    • Architectural features
    • Open Q&A

    Next Steps & Moving Forward:

    The next steps include formalizing bridge type selection, preparing a PS&E (plans, specifications and estimate), then completing and submitting the National Environmental Protection Act (NEPA) documents for review and approval. Final approval may require 18 months or more.

    Once the NEPA documents have been approved, the design will proceed to completion with intermediate reviews by County staff and Caltrans. Ideally, the project would be released for bids in the fall so that construction could begin the following spring.

    Contact Information

    Business Hours
    Monday – Friday
    8:00 AM – 2:00 PM

    Lobby Hours temporarily reduced as of 8/30/21 until further notice

    Contact us by Phone
    Office Location
    La Plaza B
    2300 County Center Drive
    Suite B 100
    Santa Rosa, CA 95403
    38.462023, -122.725381

    Standard Plans

    Construction Standards for County Roads


    Standard plans for construction of roads and related structures.